The structure of 5-[[2(R)-[1(R)-[3,5-bis(trifluoromethyl)phenyl]ethoxy]-3(S)-4-fluorophenyl-4-morpholinyl]methyl]-1,2-dihydro-3H-1,2,4-triazole-3-one (i.e., aprepitant) is as follows:

Aprepitant is the first substance P/neurokinin 1 (NK1) receptor antagonist developed by Merck & Co., which has selectivity and highly affinity for NK1 receptor, and has no affinity for 5-HT3, dopamine and corticosteroid receptors. Aprepitant was first approved by FDA in March 2003 for marketing in the United States, and was then successively marketed in other countries in the world, which is mainly used for the treatment of nausea and vomiting induced by chemotherapy, as well as for the treatment of nausea and vomiting after surgical operations.
There are three chiral centers in the chemical structure of aprepitant, which can be resolved to be formed by fragment A connected with fragment B.

The process for connecting fragments A and B in currently known literatures includes the following two methods.